Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
  • C08J7/04—Coating
  • C08J7/043—Improving the adhesiveness of the coatings per se, e.g. forming primers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
  • C08J7/04—Coating
  • C08J7/046—Forming abrasion-resistant coatings; Forming surface-hardening coatings
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/31507—Of polycarbonate
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/31511—Of epoxy ether
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/31511—Of epoxy ether
  • Y10T428/31515—As intermediate layer
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/31533—Of polythioether
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/31652—Of asbestos
  • Y10T428/31663—As siloxane, silicone or silane
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/31855—Of addition polymer from unsaturated monomers
  • Y10T428/31909—Next to second addition polymer from unsaturated monomers
  • Y10T428/31928—Ester, halide or nitrile of addition polymer
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/31855—Of addition polymer from unsaturated monomers
  • Y10T428/31935—Ester, halide or nitrile of addition polymer

Definitions

• the invention concerns a transparent plastics molding and more particularly a molding carrying a heat absorbing coating and a scratch-resistant coating.
• Transparent moldings comprising a polymeric base material and at least one coating formed thereon is disclosed.
• the coating includes a primer coat that containing an epoxy and/or acrylic resin is disposed on at least one surface of the base material, a heat-absorbing coating which contains a polythiophene compound and a scratch-resistant coating.
• the coating contains no primer and the heat absorbing coating contains a polythiophene compound.
• aqueous/alcoholic solutions of polythiophenes are deposited on a transparent glass sheet and the solvent is evaporated at room temperature.
• the dry thickness of the coating is about 0.2 ⁇ m.
• the glass sheet is pressed with a polyvinylbutyral film and a further glass sheet at 145° C./10 bar.
• Heat-absorbing composite glass sheets are known from DE 42 26 757 A1, for instance.
• DE 41 29 282 A1 discloses that transparent plastics sheets of polycarbonate or polymethyl methacrylate can be coated with polythiophenes for thermal insulation, and can optionally be provided with an acrylate- or polyurethane-based protective coating.
• This specification gives an example of a polycarbonate to which a solvent-containing primer based on polyvinyl acetate is first applied, followed by drying of the primer and the application of a solvent-containing coating of 3,4-ethylene dioxythiophene and volatilization of the solvent.
• the polycarbonate film which is coated in this manner exhibits infrared-absorbing properties.
• the underlying object of the present invention is thus to provide forms of application for known substances which absorb infrared light on plastics such as polycarbonates and poly(meth)acrylates.
• a transparent plastics molding comprising a polymeric base material (B) and at least one coating which is formed thereon, wherein a primer coat (G) containing an epoxy and/or acrylic resin is disposed on at least one side of the base material (B), on the surface of which primer coat a heat-absorbing coating (Z) is disposed which contains a polythiophene compound, and a scratch-resistant coating (K) is formed over the intermediate coating (Z).
• a transparent plastics molding comprising a polymeric base material (B) and at least one coating which is formed thereon, wherein a primer coat (G) containing an epoxy and/or acrylic resin is disposed on at least one side of the base material (B), on the surface of which primer coat a heat-absorbing coating (Z) is disposed which contains a polythiophene compound, and a scratch-resistant coating (K) is formed over the intermediate coating (Z).
• a transparent plastics molding comprising a polymeric base material (B) and at least one coating formed thereon, characterized in that a heat-absorbing coating (W), which is obtainable by hardening an aqueous dispersion containing an epoxy and/or acrylic resin and a polythiophene compound, is disposed on at least one side of the base material (B), and a scratch-resistant coating (K) is formed over the heat-absorbing coating (W).
• a heat-absorbing coating which is obtainable by hardening an aqueous dispersion containing an epoxy and/or acrylic resin and a polythiophene compound
• the plastics molding according to the invention may comprise two different types of coating structure.
• an acrylic and/or epoxy resin-based primer coat (G) is first applied to a plastics substrate (B) and is hardened.
• Water-based acrylic or epoxy resin systems i.e. those with little or no solvent content, are preferred in this respect.
• a heat-absorbing intermediate coating (Z) which contains a polythiophene compound is then applied to said primer coat (G).
• This coating composition is also present in the form of an aqueous system, i.e. it has little or no solvent content.
• a scratch-resistant coating (K) is applied to the heat-absorbing intermediate coating (Z), and protects the underlying coatings, particularly the intermediate coating (Z) which contains the sensitive polythiophene compound, from mechanical damage and UV radiation.
• the molding according to the invention which comprises the coating structure described above is distinguished by uniform wettability of the primer coat (G) by the coating composition for the intermediate coating (Z), which contains a polythiophene compound. It is also distinguished by the outstanding adherence of the individual coatings to each other and by its excellent heat-absorbing properties as measured by TSET (Total Solar Energy Transmission).
• the heat-absorbing coating (W) which contains a polythiophene compound is applied directly, i.e. without a prior primer coat, to the plastics substrate (B).
• a coating composition which contains an epoxy and/or acrylic resin and a polythiophene compound is applied to the plastics substrate (B) and hardened.
• the coating composition is applied as an aqueous system, e.g. as an aqueous dispersion, since it is only in this manner that a uniform distribution of the polythiophene compound in the acrylic or epoxy resin, as well as good wettability, may be attained.
• the aqueous dispersion should therefore contain as little solvent as possible, preferably none at all.
• a scratch-resistant coating (K) is subsequently applied to the heat-absorbing coating (W) which is applied and hardened in this manner, in order to protect the underlying coating from mechanical damage and UV radiation.
• the molding according to the invention which comprises the coating structure described above is distinguished by outstanding bonding between the plastics substrate (B) and the heat-absorbing coating (W), by a uniform distribution of the polythiophene compound in the heat-absorbing coating (W), and by its outstanding heat-absorbing properties as measured by TSET (Total Solar Energy Transmission).
• thermoplastic materials such as those which are described, for example, in Becker/Braun, Kunststofftaschenbuch, Carl Hanser Verlag, Kunststoff, Vienna, 1992.
• a polymeric multi-layer material e.g. a double-layer body which may be obtained by coextrusion, is particularly suitable as the base material (B).
• Transparent thermoplastics are particularly suitable, e.g. those based on polycarbonates, polyester carbonates and/or polymethacrylates.
• polycarbonates which are particularly suitable include bisphenol A homopolycarbonate, and copolycarbonates based on bisphenol A and 1,1-bis-(4-hydroxyphenyl)-3,3,5-trimethyl-cyclohexane).
• the polymeric base material may exist in the form of sheets, spectacles, optical lenses, automobile window glass and plastics lens covers, for example.
• Polycarbonates in the sense of the present invention include both homopolycarbonates and copolycarbonates.
• the polycarbonates may be linear or branched, in the known manner.
• Part of the carbonate groups in the polycarbonates may be replaced by aromatic dicarboxylic acid ester groups.
• Polycarbonates of this type which contain both acid residues of carbonic acid and acid residues of aromatic dicarboxylic acids incorporated in their molecular chain, are polyester carbonates. In the sense of the present invention, these are included under the general term “polycarbonates”.
• Polycarbonates may be produced by known methods.
• suitable methods for the production of polycarbonates include the production thereof from bis-phenols and phosgene by the phase boundary method or from bisphenols and phosgene by the homogeneous phase method, which is termed the pyridine method, or from bisphenols and esters of carboxylic acids by the melt esterification method.
• These methods of production are described, for example, by H. Schnell in “Chemistry and Physics of Polycarbonates”, Polymer Reviews, Volume 9, pages 31 to 76, Interscience Publishers, New York, London, Sidney, 1964.
• the aforementioned methods of production are also described by D. Freitag, U. Grigo, P. R. Müller and H.
• melt transesterification method is described in particular by H. Schnell in “Chemistry and Physics of Polycarbonates”, Polymer Reviews, Volume 9, pages 44 to 51, Interscience Publishers, New York, London, Sidney, 1964, and is also described in DE 1 031 512 A, U.S. Pat. Nos. 3,022,272, 5,340,905 and 5,399,659.
• the polycarbonates preferably have weight average molecular weights (M w )(as determined by measuring the relative viscosity at 25° C. in CH 2 Cl 2 at a concentration of 0.5 g per 100 ml CH 2 Cl 2 ) of 12,000 to 400,000 g/mol, more preferably from 18,000 to 80,000 g/mol, and most preferably from 22,000 to 60,000 g/mol.
• M w weight average molecular weights
• Substances which are suitable for infrared absorption according to the invention include, amongst others, the polythiophenes which are known from DE 38 13 589 A1, of general formula
• A represents a C 1 -C 4 alkylene radical which is optionally substituted.
• Particularly suitable polythiophenes of general formula (I) are those in which A denotes a methylene group which is optionally substituted by alkyl groups or an ethylene-1,2 radical which is optionally substituted by C 1 to C 12 alkyl groups or by phenyl groups, or a cyclohexylene-1,2 radical, particularly a methylene-ethylene-1,2- or propylene-1,2 radical.
• R 1 and R 2 independently of each other, denote hydrogen or a C 1 to C 4 alkyl group and together denote a C 1 to C 4 alkylene radical which is optionally substituted.
• Particularly suitable polythiophenes comprising structural units of general formula (II) are those in which R 1 and R 2 , independently of each other, represent hydrogen or methyl, or together represent a methylene radical which is optionally alkyl-substituted, an ethylene-1,2 radical which is optionally substituted by a C 1 to C 12 alkyl group or by phenyl, or a cyclohexylene-1,2 radical.
• 3,4-ethylene dioxythiophene is a most particularly suitable polythiophene compound.
• the polythiophene compound is preferably used in the form of an aqueous dispersion, particularly as an aqueous dispersion of polyethylene dioxythiophene (PEDT).
• PEDT polyethylene dioxythiophene
• Suitable polymers such as polystyrene sulphonate (PSS) may be added in suitable amounts thereto. Dispersions of this type are commercially available under the trademark “Baytron®-P” of Bayer AG.
• the heat-absorbing intermediate coating (Z) is formed by the application and drying of a coating solution or composition containing at least one polythiophene compound of the type described above. Coating solutions and compositions of this type, and the production of coatings therefrom, are described in detail in DE 38 13 589 A1 and in EP 0 440 957 A2, for example.
• the heat-absorbing intermediate coatings (Z) which are particularly preferred are those which may be obtained by the application and drying of an aqueous dispersion of polyethylene dioxythiophene (PEDT), particularly in combination with a suitable polymer such as polystyrene sulphonate (PSS). Coating dispersions of this type are commercially available under the trademark “Baytron®-P” of Bayer AG.
• the heat-absorbing intermediate coating (Z) generally has a coating thickness of 0.01 to 1.5 ⁇ m, preferably 0.05 to 0.5 ⁇ m.
• the primer coat (G) which is used according to the invention contains a hardened epoxy and/or acrylic resin. It preferably has a coating thickness of less than 50 ⁇ m, more preferably less than 15 ⁇ m, most preferably less than 1 ⁇ m.
• One preferred primer coat (G) may be obtained by the crosslinking of multi-epoxyfunctional compounds, hereinafter called epoxy compounds, with what are termed hardeners, which are also called hardening agents or crosslinking agents.
• Epoxy compounds may be produced by known methods, such as those described below. They are generally produced by the reaction of epichlorohydrin with substances which contain an active hydrogen atom, according to the following reaction scheme:
• Aromatic glycidyl compounds may be used as epoxy compounds.
• Examples thereof include:
• n 0 to 15 for the industrial product
• n approx. 2 or approx. 4 or approx. 12 for what are termed technical advancement products;
• cresol novolac glycidyl ethers which correspond substantially to the following formula
• n is between 1.0 and 4.0 in industrial products
• Cycloaliphatic glycidyl compounds may also be used as epoxy compounds. Examples thereof include:
• Heterocyclic glycidyl compounds may also be used as epoxy compounds. Examples thereof include:
• Cycloaliphatic epoxy compounds which may be employed as starting materials for cycloaliphatic epoxy resins may also be used as epoxy compounds. Examples thereof include:
• Aliphatic epoxy compounds which may be employed as starting materials for aliphatic epoxy resins may also be used as epoxy compounds. Examples thereof include:
• n has a value such that the resulting (number average) molecular weight is 425 g/mol.
• All the epoxy compounds which may be used according to the invention contain at least two epoxide groups.
• Epoxy compounds which are particularly preferred are those which contain no aromatic structures. Cycloaliphatic epoxy compounds which may be employed as starting materials for cycloaliphatic epoxy resins are most particularly preferred. These provide coatings which are particularly stable to UV radiation. The production thereof is described, for example, in the Encyclopedia of Polymer Science and Engineering, Volume 6, page 336, John Wiley & Sons, and in U.S. Pat. No. 2,716,123.
• hardeners examples include anhydrides such as phthalic anhydride, tetrahydro-, hexahydro-, methyltetrahydro-, endomethylene-tetrahydro- and methylene-domethylene-tetrahydrophthalic anhydride, pyromellitic, trimellitic, benzophenone-tetracarboxylic anhydride, maleic anhydride/styrene copolymers or dodecenylsuccinic anhydride.
• anhydrides such as phthalic anhydride, tetrahydro-, hexahydro-, methyltetrahydro-, endomethylene-tetrahydro- and methylene-domethylene-tetrahydrophthalic anhydride, pyromellitic, trimellitic, benzophenone-tetracarboxylic anhydride, maleic anhydride/styrene copolymers or dodecenylsuccinic anhydride
• Suitable hardeners also include amines such as aromatic amines, cycloaliphatic amines and aliphatic amines, e.g. 4,4′-diamino-diphenylmethane and o,o′-alkyl-substituted derivatives thereof, 4,4′-diaminodiphenyl ethers, 4,4′-diaminodiphenyl sulphone, 2,4-diamino-3,5-diethyltoluene, hydrogenated 4,4′-diaminodiphenyl-methane, isophoron-ediamine, diethylenetriamine, triethylenetetramine, polyamino-amides based on diethylenetriamine or similar amines, and fatty acids.
• amines such as aromatic amines, cycloaliphatic amines and aliphatic amines, e.g. 4,4′-diamino-diphenylmethane and o
• the hardener and the epoxy compounds may be used as aqueous dispersions or in organic solvents, for example.
• organic solvents are alcohols, particularly isopropanol, ethanol, isopropyl glycol, butyl glycol, 4-hydroxy-4-methyl-2-pentanone or mixtures thereof. 4-hydroxy-4-methyl-2-pentanone is most particularly preferred.
• Hardeners and partially crosslinked epoxy compounds are marketed, for example, by Ciba Spezialitätenchemie GmbH, D-79664 Wehr, Germany, under the trademark Araldite® and hardeners, as two-component system for coating very different substrates.
• chain extension components preferably phenols
• polymerization initiators preferably phenols
• polyaddition catalysts preferably phenols
• plasticizers preferably plasticizers
• impact-resistance modifiers such as those which are known from the cited literature
• primer coat (G) may contain customary additives such as colorants, leveling agents, reactive thinners, inorganic or organic extenders and stabilizers, particularly UV stabilizer systems, and infrared absorbers.
• the surface of the substrate is usually cleaned first.
• the diluted single component composition which contains epoxy compounds and hardeners, is applied to the substrate by immersion, inundation, spraying, spin-coating or by other lacquer-coating techniques.
• the primer coat (G) is thus formed.
• the coating thickness is controlled via the extent of dilution (preferably 2 to 35% by weight solids content) and by the coating parameters.
• the primer coat (G) is preferably allowed to dry at room temperature (20 to 23° C.) until it is dust-dry. Final crosslinking is subsequently effected at an elevated temperature, preferably at 90 to 130° C.
• Primer coats (G) based on acrylic resins may also be used according to the invention.
• acrylic resin-based primer coats are described in DE 30 14 772 A1. These are formed by the application and hardening of an aqueous emulsion containing a thermosetting acrylic polymer and a hydroxyether or alkanol comprising 1 to 4 carbon atoms.
• the primer coats described in the above patent have to contain a UV absorber such as benzylidene malonate or cyanoacrylate, this component is in fact recommended, but is not absolutely necessary, in the acrylate-based primer coat which is used according to the present invention.
• One acrylate-based primer which is preferably used according to the invention generally contains from about 1 to about 10% by weight of thermosetting acrylic solids, from about 0 to about 10% by weight of at least one compound which absorbs compound which absorbs UV light from the group comprising benzylidene malonate and cyanoacrylate, from about 20 to about 40% by weight of a hydroxyether or alkanol comprising 1 to 4 carbon atoms, and from about 40 to about 79% by weight of water.
• the thermosetting acrylic solids are placed in a vessel in the form of a concentrated emulsion of a thermosetting acrylic polymer.
• This thermosetting acrylic polymer emulsion concentrate contains a thermosetting acrylic polymer dispersed in water.
• the polymer is generally dispersed in water in the form of discrete spherical particles (of about 0.1 ⁇ m diameter).
• thermosetting acrylic polymers are known to those skilled in the art. Examples of thermosetting acrylic materials which may be used for carrying out the invention in practice are listed in the Encyclopedia of Polymer Science and Technology, Volume 1, Interscience Publishers, John Wiley & Sons, Inc., 1964, pages 273 et seq., in The Chemistry of Organic Film Formers, D. H. Solomon, John Wiley & Sons, Inc., 1967, pages 251 et seq., and in the literature references cited therein.
• thermosetting acrylic polymers comprise (1) acrylic copolymers which contain reactive functional groups which are capable of reacting with each other with crosslinking, (II) acrylic copolymers which contain reactive functional groups and to which a suitable, compatible, crosslinking agent is added which reacts with the functional groups with crosslinking, and (III) a mixture of two polymers which contain functional reactive groups which are capable of crosslinking.
• thermosetting typically those between, for example, functional epoxide groups and amino groups, epoxide groups and anhydride groups, epoxide groups and carboxyl groups, including phenolic hydroxyl groups, epoxide groups and N-methylol or N-methylol ethers, carboxyl groups and N-methylol- or N-methylol ether groups with interaction between the carboxyl and isocyanate groups; reactions between hydroxyl groups, e.g. of polyols, and isocyanate groups, and reactions between amino groups and N-methylol- or N-methylol ether groups.
• the acrylic fraction is the major constituent, i.e.
• the requisite functional group in the acrylic polymers which is the basis of thermosetting acrylic polymers, is introduced by using a monomer which introduces the necessary reactive functional group into the polymer chain during copolymerization.
• This copolymerizable monomer which provides a functional group, is usually present in small amounts, i.e. of the order of 25% by weight or less, and is typically present in an amount between about 1 and 20% of the weight of monomer which is polymerized.
• Examples of monomers which introduce the requisite functional groups include glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, dimethylaminoethyl methacrylate, vinylpyridine, tert.-butyl-aminoethyl methacrylate, maleic anhydride, itaconic anhydride, allyl alcohol, monoallyl ethers of polyols, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate, acrylamide, methacrylamide, maleamide, N-methylolmethacrylamide, vinyl isocyanate and allyl isocyanate.
• the other monomer which polymerizes together with the monomers which provide the functional group, is a low molecular weight (C 1 to C 2 ) alkyl ester of acrylic acid or mixtures thereof, e.g. methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate or mixtures thereof, in an amount within the range between about 75 and about 99 parts, typically between about 80 and about 97 parts.
• thermosetting acrylic polymer emulsion concentrates which may generally be used for carrying out the present invention in practice are usually commercially available. In general, these emulsion concentrates contain from about 40 to about 55% solids. With regard to the composition of the primer emulsion medium, however, it has proved to be desirable for the primer emulsion medium to contain from about 1 to about 10% by weight acrylic solids. Thus it is generally necessary to dilute these commercially available emulsion media by adding additional water. Moreover, these primer emulsion media may contain hardening catalysts for the thermosetting acrylic polymers. If a catalyst such as this is present, it is contained in an amount of 0.05 to 2% by weight with respect to the weight of the acrylic solids. Examples of catalysts such as these include toluenesulphonic acid, citric acid, phosphoric acid, etc.
• a second component of the primer emulsion medium is a hydroxyether or an alkanol comprising 1 to 4 carbon atoms.
• the hydroxyethers may be represented by the general formula
• R 1 is an alkyl or an alkoxyalkyl radical containing from 1 to about 6 carbon atoms and R is an alkylene radical containing from 1 to about 6 carbon atoms, with the proviso that the sum of the carbon atoms in R 1 and R 2 ranges from 3 to about 10.
• the alkanols which contain from 1 to 4 carbon atoms comprise methanol, ethanol, propanol, isopropanol, butanol, tert.-butanol and the like.
• the presence of the aforementioned hydroxyether or alkanol in amounts ranging from about 20 to about 40% by weight of the primer emulsion medium is critical for the satisfactory performance of the primer emulsion medium in order to form an effective primer coat.
• the concentration of the acrylic polymer solids in the primer emulsion medium is generally quite important.
• Primer emulsion media which contain from about 2 to about 6% by weight of thermosetting acrylic polymer are preferred.
• Benzylidene malonate and ⁇ -cyanoacrylate may be used, amongst others, as compounds which absorb UV light.
• a thin coating of the primer medium is applied to the substrate by any of the well known methods, such as spraying, immersion, roller coating and the like.
• the primer medium is applied in an amount which is sufficient to provide a hardened primer film with a thickness from about 0.254 to about 2.54 ⁇ m, preferably from about 0.51 to 2.03 ⁇ m.
• the bulk of the water and of the hydroxyether or alkanol is then removed by evaporation, e.g. by air drying or by gentle warming, in order to leave behind a uniform solid coating of thermosetting acrylic polymer and optionally of the compound which absorbs UV light.
• thermosetting acrylic polymer is then hardened by heating the solid coating to a temperature from about 90 to about 130° C., whereby a primer coat is formed which preferably contains, in percentages by weight, from about 10 to about 90%, most preferably from about 50 to about 70%, of a thermally hardened acrylic resin and preferably from about 10 to about 90%, most preferably from about 30 to about 50%, of at least one compound which absorbs UV light.
• the production of the primer coat thus involves (I) the application, to a substrate, of a primer emulsion medium which, in percentages by weight, contains (a) from about 1 to about 10% of a thermosetting acrylic polymer, (b) from 0 to about 10% of at least one compound which absorbs UV light, which is selected from the group comprising benzylidene malonate and cyanoacrylate, (c) from about 20 to about 40% of a hydroxyether or of an alkanol comprising 1 to 4 carbon atoms, and (d) from about 40 to about 79% water, (II) the evaporation of a considerable proportion of the water and hydroxyether or alkanol from the primer emulsion medium with the formation of a solid coating comprising the thermosetting acrylic polymer and optionally the compound(s) which absorbs/absorb UV light, and (III) heating the thermosetting acrylic primer coating.
• a primer emulsion medium which, in percentages by weight, contains (a) from about 1 to about 10% of
• the heat-absorbing coating (W) may be obtained by the application and hardening of an aqueous dispersion containing an epoxy and/or acrylic resin and a polythiophene compound.
• Epoxy and acrylic resins which are particularly suitable include the epoxy and/or acrylic resins which may be used in the primer coating (G) and which were described above.
• the polythiophene compounds described above are particularly suitable as polythiophene compounds.
• an aqueous dispersion of polyethylene dioxythiophene (PEDT) is used as the polythiophene compound; suitable polymers such as polystyrene sulphonate (PSS) may be added thereto according to need.
• PEDT polyethylene dioxythiophene
• PSS polystyrene sulphonate
• the coating composition for the heat-absorbing coating (W) preferably contains from 2 to 35% by weight, particularly 3 to 10% by weight, of an acrylic and/or epoxy resin, from 0.5 to 5% by weight, particularly 1 to 2% by weight, of a polythiophene compound, and from 97 to 60% by weight, particularly 96 to 70% by weight, of water.
• the coating composition may be produced by the method described for the primer coat (G), wherein the polythiophene compound may be added to the other components in an arbitrary manner and sequence.
• the application and hardening of the heat-absorbing coating (W) may also be effected in the manner described for the primer coating (G).
• the hardened heat-absorbing coating (W) generally has a coating thickness from 0.2 to 2.5 ⁇ m, preferably from 0.5 to 2.0 ⁇ m.
• All polymeric materials which, due to their hardness, are capable of protecting the underlying coatings from mechanical damage are suitable as a scratch-resistant coating (K).
• K scratch-resistant coating
• Substances which are particularly suitable for this purpose include soluble, crosslinking or thermoplastic lacquers, e.g. acrylate-, polyurethane- or polysiloxane-based lacquers, nano lacquers, and products which may be crosslinked by UV or by an electron beam.
• Examples of particularly suitable scratch-resistant coatings (K) are those described in WO 99/10441 and WO 99/11725; these are scratch-resistant coatings based on silanes which contain epoxide groups.
• the latter may be obtained, for instance, by the application and hardening of a coating composition containing
• At least one silicon compound (A) which comprises at least one radical which contains an epoxide group and which cannot be cleaved by hydrolysis
• a particulate material (B) which is selected from oxides, hydrated oxides, nitrides and carbides of Si, Al and B and of transition metals and which has a particle size within the range from 1 to 100 nm,
• At least one hydrolyzable compound (D) of Ti, Zr or Al At least one hydrolyzable compound (D) of Ti, Zr or Al.
• composition preferably present in the following ratio:
• compound (A) is a compound of general formula R 3 SiR′, wherein the R radicals are identical or different and represent a group which may be hydrolyzed, preferably a C 1-4 alkoxy group, and R′ represents a glycidyl or a glycidyloxy-(C 1-20 ) alkylene radical.
• compound (B) is an oxide or a hydrated oxide of aluminum.
• compound (C) is a compound of general formula SiR 4 , wherein the R radicals are identical or different and represent a group which may be hydrolyzed, preferably a C 1-4 alkoxy group.
• compound (D) is a compound of formula AlR 3 , wherein the R radicals are identical or different and represent a group which may be hydrolyzed, preferably a C 1-6 alkoxy group, a C 1-6 alkoxypropanolate group or a C 1-6 alkoxyethanolate group.
• the scratch-resistant coating (K) which is based on silanes which contain epoxides is preferably applied to an acrylic resin- or epoxy resin-based thermally insulating coating (W), or to a polythiophene intermediate coating (Z) which adheres to an acrylic resin- or epoxy resin-based primer coat (G). Optimum bonding-in of the polythiophene compound is thereby achieved.
• a scratch-resistant coating (K) which is based on silanes which contain epoxide groups is applied to an epoxy resin-based thermally insulating coating (W) described above, or is applied to a polythiophene intermediate coating (Z) which adheres to an epoxy resin-based primer coat (G).
• Examples of other particularly suitable scratch-resistant coatings are the polysiloxane-based scratch-resistant coatings which are described in EP 0 350 698 A2.
• R is selected from the group consisting of hydrogen, alkyl groups which contain from about 1 to 8 carbon atoms, and aromatic groups which contain from about 6 to 20 carbon atoms.
• the polysiloxane-based scratch-resistant coating (K) is preferably applied to an acrylic resin-based thermally insulating coating (W), or to a polythiophene intermediate coating (Z) which adheres to an acrylic resin-based primer coat (G).
• the optimum bonding-in of the polythiophene compound is thereby achieved.
• the polysiloxane-based scratch-resistant coating (K) is applied to an acrylic resin-based thermally insulating coating (W) according to DE 30 14 772 A1, or is applied to a polythiophene intermediate coating (Z) which adheres to an acrylic resin-based primer coat (G) according to DE 30 14 772 A1.
• the scratch-resistant coatings (K) may also contain customary additives, such as colorants, leveling agents, UV stabilizers, photo-initiators, photo-sensitizers (if it is intended to harden the composition photochemically) and thermal polymerization catalysts.
• customary additives such as colorants, leveling agents, UV stabilizers, photo-initiators, photo-sensitizers (if it is intended to harden the composition photochemically) and thermal polymerization catalysts.
• the scratch-resistant coating (K) preferably contains one or more UV absorbers, in order to protect the polythiophene compound contained in the underlying coating from decomposition by UV radiation.
• Application to the substrate is effected by standard methods of coating, such as immersion, painting, brushing, application by doctor blade, rolling, spraying, falling film application, spin coating and centrifugal application.
• the coated substrate is hardened, optionally after a prior preliminary drying step at room temperature.
• Hardening is preferably effected thermally at temperatures within the range from 50 to 300° C., particularly from 70 to 200° C. and most preferably from 90 to 180° C., optionally under reduced pressure. Under these conditions the time of hardening is preferably less than 200 minutes, more preferably less than 100 minutes and most preferably less than 60 minutes.
• the coating thickness of the hardened coating preferably ranges from 0.5 to 100 ⁇ m, more preferably from 1 to 20 ⁇ m and most preferably from 2 to 10 ⁇ m.
• hardening may also be effected by irradiation, optionally followed by thermal post-hardening.
• a 1.3% aqueous dispersion of polyethylene dioxythiophene (PEDT) and polystyrene sulphonate (PSS) (pH 1 to 2), which is obtainable from Bayer AG under the trademark Baytron®-P was used as the IR-absorbing polythiophene compound.
• PEDT polyethylene dioxythiophene
• PSS polystyrene sulphonate
• the coating thickness of the heat-absorbing intermediate coating (Z) after drying was 80 nm.
• priming lacquer G1 In order to produce priming lacquer G1, the solvent, namely 4-hydroxy-4-methyl-2-pentanone, water and emulsifying agent were placed in a vessel at room temperature and the other additives were added in an arbitrary sequence with stirring. The batch was stirred until a clear, homogeneous dispersion was obtained. The dispersion was stored at room temperature.
• Heat-absorbing coating (W1) was produced by the application and hardening of a coating composition which in addition to the aforementioned constituents of priming lacquer G1 contained 1.0 parts by weight of Baytron®-P as an IR-absorbing polythiophene compound in the solid film.
• Heat-absorbing coating (W2) was produced by the application and hardening of a coating composition which in addition to the aforementioned constituents of priming lacquer G2 contained 1.0 parts by weight of Baytron®-P as an IR-absorbing polythiophene compound in the solid film.
• Primer coats (G) and heat-absorbing coatings (W) were formed by inundation, to give a coating thickness of 0.8 ⁇ m.
• UV absorber 4-[ ⁇ -(tri-(methoxy/ethoxy)silyl)propoxy]-2-hydroxybenzophenone were added. The mixture was stirred for two weeks at room temperature.
• the composition had a solids content of 20% by weight and contained 11% by weight of the UV absorber with respect to the solids constituents.
• the coating composition had a viscosity of about 5 cSt at room temperature.
• Moldings 2, 3 and 5 according to the invention were distinguished by a very uniform distribution of the polythiophene compound on the surface of the respective substrate, outstanding adhesion between the individual coatings, and by excellent TSET values ranging from 58 to 64.

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• 2001
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